brunner



H. R. BRUNNER. AIR PREHEATING DEVICE FOR FUARNA'CES AND THE LIKE. APPLICATION FILED OCT. 7, 1915.

1,354,950, Patented 001;. 5,1920;

5 I 5 4 SHEETSSHEET 1| s 1 M c d. L IsfiaeT m H. R. BRUNNER.

AIR PREHEATING DEVICE FOR FURNACES AND THE LIKE. APPLLCAIION FILED ocr. 7, 1915.

1,354,950, Patented 001:. 5,1920.

4 SHEETS-SHEET 2.

wibneoou W H. R. BRUNNER. AIR PREHEATING DEVICE'FOR FURNACES AND THE LIKE.

APPLICATION FILED OCT. 7, I915.

Patented Oct. 5, 1920.

4 SHEETS-SHEET 3.

atknncg H. R. BRUNNER. AIR PREHEATJNG DEVICE FOR FURNACES AND THE LIKE.

APPLICATION FILED OCT- 7, I9l5. 1,354,950.

wifneweo Patented Oct. 5,1920.

4 SHEETS-SHEET 4.

UNITED STATES (EFFICE.

HERBERT R. BRUNNER, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, T0 JOHN F. BLANCHARD, OF NEW YGRK, N. Y.

AIR-PREHIEATING DEVICE FOR FURNACES AND THE LIKE.

Specification of Letters Patent.

Application filed October 7. 1915.

To all whom it may concern:

Be it known that I, HERBERT R. BRUNNER, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Air-Preheating Devices for Furnaces and the like, of which the following is a specification.

This invention relates to air preheating devices for furnaces and the like.

Heretofore, as far as I am aware, the attention of inventors in this art has been directed merely to baffling the preheater casing or element for the purpose of retarding the infiowing air, so as to heat the same more effectively, orin other words, such devices have usually been provided with retarding plates or bafiles, variously arranged within the casing to keep the air from going directly through it from the inlet to the outlet. Some of such devices by a peculiar arrangement of the baffles, are provided with channels of increasing cross sectional area, or rather an arrangement of bafiles whereby channels of increasing cross sectional area are formed, with the idea of permitting the air to expand as it passes through the easing, from the inlet to the outlet.

Such devices, I have demonstrated by experiment, are only partially efficient within a very narrow range of draft, and in fact, so inefficient that their use becomes a detriment outside of such draft range, rather than an advantage.

The object of my invention is to provide a preheating element for use in combination with the tire boxes of stoves, furnaces, steam boilers and the like, Whose action. will be practically automatic in meeting the changing or variable draft conditions from the minimum to the maximum, the preheater being designed to deliver under any one of the variable draft conditions of the fire box, the properly proportioned amount of adequately preheated air.

I have desi ned the element about to bedescribed so t at when the draft in a particular furnace or fire box is increased over that normally prevailing for the average load conditions, a slightly increased amount of air, adequately preheated, will be drawn into the fire box through the preheater, but this increased amount will not be proporlatented Oct. 5, 1920.

Serial No. 54,631.

tionate to the increase in the draft by reason of the frequent reversing of the air travel in the element, the length of travel, and the size of outlet openings, which considerations are important features of this invention.

It is a fundamental proposition that when gases are made to travel through a channel of given cross sectional area, and of a given appreciable length, the increase or diminution in the length of travel necessarily entails variable frictional loss, and this frictional loss varies directly as the square of velocity and this frictional loss is furtherincreased or diminished in proportion to the number of reversals the air undergoes in travel from the inlet to the outlet.

In my invention, this fact is recognized, and the construction is such that when the draft in the fire box undergoes a change, a corresponding change in the velocity of the air, passing through the preheating element, is brought about, governed always by the internal construction which modifies this change of velocity, which, as I have said, will be in proportiontothe combustion requlrements.

A necessary incident to the present invention is that the device provides an auxiliary air supply, and for that reason, a given load can be carried by a given fuel bed with less stack draft pull than would berequired if it were necessary to draw all of the required air through the fuelbed and this obviates the disadvantages and loss that necessarilv accompany strong draft pull.

In the drawings illustrating the invention-' Figure l is a vertical central section of a representative embodiment of the preheating element, showing thesame attached to a section or fragment of a furnace door, there being shown in the door, the usual damper 'or,

valve.

Flg. 2 is a view looking into the entrance chamber the outer and inner baflie plates being partly broken away to Show the direc- Fig. 5 is a section taken or fine cc of Fig. 1;

Fig. 6 is a similar section taken on line dd of Fig. 1;

Fig. 7 is a similar section taken on line e-e of Fig. 1, or through the last compartment in the second chamber of the preheater;

Fig. 8 is a side elevation of a furnace, partly broken away, showing a preferred form of apparatus, or the form shown in Fig. 1, secured to the'furnace, there being also shown, the draft apparatus in the way of ash pit, fuel door and stack dampers.

Referring to the drawings, the numeral 1 designates the casing, which is preferably formed of cast metal, with the various chambers and battle walls cast integral, so as to conduct the heat to the air passing through the casing. The numeral 2 designates what I will term the entrance chamber. This is preferably rectangular in form, as shown in Fig. 2, and formed of top and bottom flanges 3, and end flanges 4, there being lugs 5 cast on the top flange 3 and lugs 6 integral with the end flanges 4, which lugs are for the purpose of affording means of securing the whole casing to the furnace door 7; Bolts 8 may be employed for this purpose, and it will be understood that the whole de-- vice preferably, is carried by the furnace door, and swings into and out'of the position with relation to the firebox.

Within the entrance chamber 2, I provide two bafile plates 9 and 10. The front plate 9 fills the front part of the chamber 2, with the exception of a longitudinal passage 11, formed between the upper edge of said plate, and the upper flange 12 of the plate 10, and the plate 10 fills the space within the entrance chamber, with the exception of a horizontal opening 13, which is similar to the opening 11. The rear wall 14 of the entrance chamber has integral therewith, a baflle wall 15, and extends forwardly, where its inner edge abuts against the inner face of the plate 10. This wall 15 is formed of horizontal and vertical portions a, b and a, so that the air in passing into the rear part of the entrance chamber, will be prevented from passing directly to the central outlet 16, which is formed through a central boss 17, which establishes communication between the entrance chamber and the circular chamber 18, there being, in addition to boss 17, a number of solid bosses 18' which rigidly connect the entrance chamber with chamber 18. This chamber 18 is preferably circular in form and provided with circularly arran ed baflie walls, as will be described. is chamber 18 is connected with a third or last chamber 19, by a central boss 20 having therethrough a passage 21, through which the chamber 19 is placed in communication with the rear compartment of chamber 18.

The numeral 22 designates the distributer end, which is in communication with the rear compartment of the chamber 19 through passage 23. This distributer end is provided with a plurality of apertures 24, through which the highly and adequately preheated air is delivered into the fire box to mingle with the products of combustion therein.

Referring particularly to Fig. 1, the numerals 25, 26 and 27 designate three comartments in the chamber 18, which compartments are formed by the front and rear walls 28 and 29 of the chamber 18, and the partitions 3O and'3l', to ether with the circular outer wall 32 o the chamber. As shown in Figs. 1 and 3, the compartment 25 has therein a baffle Wall 33'which is substantially helical in form, thus providing a continuous helical passage 34. The central portion 35 of the bafile wall registers with the passage 16, thus delivering the air to the inner end of the helical passage 34, and by reason of the shape of the wall, the air is compelled to travel in circular direction throughout the channel 34 in the direction of the arrows.

The upper end of the wall 33 has integral therewith a short radial wall 36, which is also integral with the circular outer wall of the casing. The numeral 37 designates a passage through the upper part of the inner partition 30, by which communication is established between the compartments 25 and 26. Within the compartment 26, I arrange two substantially radial bafiie walls 38 and 39, the inner end of the wall 38 being slightly curved as indicated at 40, while the inner end of the wall 39 is provided with a short radial wall 41, which, in connection with the concentrically arranged walls about to be described, serve to properly guide and to insure the proper circulation for the air passing through the compartments. The walls 38.and 39 are integral with the outer circular wall of the casing.

The numeral 42 designates a concentric baffle wall within the compartment 26, which wall is integral with the radial wall 38, near the periphery of the casing. This wall 42 ends short of the radial baffle wall 39, so that a passage 43 is formed by which communication between the outer channel 44 and intermediate channel 45 is established. This intermediate channel 45 is formed by the wall 42 and the central or inner concentric Wall 46, which wall is integral with the wall 39 and stops short of the wall 38, thus forming a passage 50, which establishes communication between the channel 45 and the inner channel 51, which in turn communicafes, through a passage 52, between the parts 41 and 40, with a radial channel 53, leading to the passa e 54, which is made in the upper part 0 the partition 31, thus establishing communication between the compartments 26 and 27. Within the compartment 27, I arrange a helical wall 55, between the convolutions of which and the outer wall of the casing, is formed a continuous helical channel 56. The inner portion of the bafile wall indicated at 57 registers with the passage 21, in the boss 20, by which communication between the chambers18 and 19, is established. The wall 55 is provided at its upper end, with an integral radial wall 58, which directs the flow of air coming through the passage 54, through the channel 56, in the direction of the arrows.

The chamber 19 is provided witha central partition 59, which, together with the front and rear walls 60 and 61, and the circular wall 62 of the chamber 19, forms compartments 63 and 64. The air is delivered centrally into the compartment 63, and passes through the channel 65, formed by the helical baffle wall 66, and the circular outer wall of the casing. This baffle wall 66, is provided at its upper end with an integral radial wall 67, which forms the upper end of the channel, there being a passage 68 through which communication between the compartments 63 and 64 is established, the passage being through wall 59. The air de-- livered through the passage 68 passes into the last compartment 64, at the upper portion thereof, and by reason of the provision of a concentric baffle wall 69, is caused to travel in a circular direction through the channel 70, formed between the outer circular wall of the casing, and the baffle wall 69, which bafile wall 69 stops short of a short integral radial wall 71, thus forming a passage 72, communicating with the distributer end through the passage 23, from which distributer end, as before suggested, the adequately and highly preheated air is delivered into the fire pot of the furnace.

From the foregoing description it will be seen that the various compartments are in axial and peripheral communication thus causing alternate reversals of the air currents in their passage through the device, with attending efiicient preheating, and further thatthe air currents are caused to traverse centrifugal and centripetal paths in reverse directions throughout the structure, the terms centrifugal and centripetal being employed to designate directions of movements of the air currents and not forces impelling them.

It is believed that throughout the descrip-- tion of the device, the operation has been incidently suggested to such extent as to render it unnecessary to go into an elaborate description of operation, it being obvious that the air in passing into the element, is passed back and forth many times within the casing, while in contact with highly heated surfaces, with the joint design of both heating and controlling the flow, so

that it will be in proportion to the draft pull of the particular furnace or class of furnace for which the particular device is intended.

In practical operation, an element is designed for use in connection with a fire box, of known capacity, between the minimum and maximum load, the element being designed to respond automatically, to the variations in the draft of the furnace between the minimum and the maximum, as the result of the use of the element. The amount of air supplied to the products of combustion will vary according to the draft, as for instance, as has been suggested in the first part of this specification, when the draft pull is comparatively great, or a furnace is working under heavy load, an additional amount of highly preheated air will be supplied, but not an excessive amount, or an amount that would chill the fire. This is on account of the frictional loss occasioned by the increased draft.

Referring to Fig. 8, the numeral 192 represents a furnace of ordinary construction, and 193 designates the fire door thereof, with the preheating elements secured thereto. The numeral 194 designates the ash pit damper and 195 designates the usual stack, and 196 designates the stack damper therein, all of which furnace apparatus may be of any approved construction, this illustration being provided merely to show clearly the application of the apparatus.

It will be seen from the foregoing, that the air, in passing through the preheating element, is caused to travel in several different directions or is subjected to sharp reversals, in its circumferential travel within the casing, and is also caused, at intervals to travel at right angles to its general line of travel in passing through the openings in the partitions, and in passing from one compartment" to the other, and from one chamber to the other, which method of traveling, together with the proper proportioning in cross sectional area of the channels through which the air passes, limits, by a static means, that is to say, without the aid of movable dampers or the like, the acceleration of the flow in the air through the casing, which in a particular device, is relative to the heating conditions in the furnace.

Having thus described my invention, what I claim is:

1. A device for preheatin air for aiding combustion in furnaces an the like, comprising a casing adapted to be attached to the furnace and to extend into the fire pot thereof, comprising a casing formed with an entrance chamber, and a second chamber communicating with the entrance chamber and having a partition therein which, together with the walls of the second chamber divide the aid chamber into compartments, baflie walls integral with the partition and with the walls of the casing, an opening in the partition whereby the compartments are placed in intercommunication, the said baffle walls being so arranged that the air will be caused to circulate centrifugally in one direction and completely through the first compartment and passing throughthe openmg in the partition will be caused to circulate centripetally in the opposite direction in the second compartment, and an outlet in the second compartment for the discharge of preheated air.

2. A device for aiding combustion in furnaces and the like, comprising a casing havmg an entrance chamber, a plurality of circular chambers one of which communicates with the entrance chamber, said chambers also communicating with each other, said last mentioned chambers being separated from each other so as to permit the products of combustion of the furnace to pass between said chambers, partitions within said chambers dividing them into compartments, circularly arranged bafile walls integral with the partitions and with the walls of the casing, said baffle walls forming continuous channels leading from the center of one compartment to the outer portion of the next compartment, there being openings in the partitions whereby the compartments are placed in intercommunication, the arrangement of the baffle walls and openings being such that the air circulating through the casing will be caused to travel back and forth therein in opposite directions.

3. An air preheating device for furnaces and the like comprising intake and discharge chambers, intercommunicating compartments, and means for causing air currents to traverse centrifugal and centripetal paths in reverse directions from the iritake to the discharge.

4. An air preheating device for furnaces and the like comprising intake and discharge chambers, compartments having channels in peripheral communication and arranged to cause centrifugal and centripetal movements of air currents in defined paths in reverse directions from the influent to the effluent end of the structure, the channels being so proportioned in capacity relative to the draft requirements that only the required amount of preheated air to insure proper combustion, will be delivered to the furnace irrespective of draft conditions.

5. An air preheating device for furnaces and the like comprising a structure provided at one end with an intake chamber, at its other end with a discharge chamber, longitudinally of its length with an interrupted passage between the intake and discharge, and with a series of chambers formed with compartments having peripheral communication; and means whereby the air currents are caused to traverse defined centrifugal and centripetal paths in reverse directions from the intake to the discharge.

-6. An air preheating device for furnaces and the like comprising an intake chamber provided with bafiles, a discharge chamber, an interrupted passage connecting the intake and discharge chambers, a plurality of spaced chambers surrounding the passage and having axial communication, the chambers having compartments therein having baflles and defining curvilinear channels running in opposite directions to impart reverse travel to the air currents.

7. In combination with a furnace and the draft apparatus thereof, an air preheater, adapted to be secured to the furnace and to extend into the fire box thereof, comprising a casing havingintercommunicating channels formed by bafile walls that are disposed to impart centrifugal and centripetal movements to the air currents in defined paths, the channels being in cross sectional area, so proportioned to the draft requirements of the furnace, that the variation in the draft from the minimum to the maximum load will cause limitation of acceleration in the flow of air' through the casing relatively to the heat conditions in the furnace, whereby the required amount of adequately preheated air is delivered in the fire box at all stages of combustion from a minimum to a maximum load.

In testimony whereof I aflix my signature in presence of two witnesses.

HERBERT R. BRUNNER.

Witnesses:

FRANCIS L. MAGUIRE, Trrnm W. JOHNSON. 

